Mercer J G, Moar K M, Logie T J, Findlay P A, Adam C L, Morgan P J
Molecular Neuroendocrinology Group, Aberdeen Centre for Energy Regulation and Obesity, Rowett Research Institute, Bucksburn, Aberdeen, Scotland AB21 9SB, United Kingdom.
Endocrinology. 2001 Oct;142(10):4173-81. doi: 10.1210/endo.142.10.8454.
Male Siberian hamsters undergo physiological weight change in changing photoperiod. Weight loss was induced by food restriction in long days to mimic short-day weight loss, or by food restriction superimposed on short-day weight loss, to test the hypothesis that the hypothalamus differentiates between weight change induced by imposed negative energy balance (inappropriate body weight) and seasonal, appropriate, body weight change, even when these are of similar magnitude. Short-day weight loss was accompanied by reduced POMC and leptin receptor (OB-Rb) mRNA in the arcuate nucleus but elevated cocaine- and amphetamine-regulated transcript. Melanocortin 3-receptor gene expression was reduced in the arcuate nucleus but elevated in the ventromedial nucleus compared with ad libitum-fed long-day controls. Weight loss in long-day restricted animals generated a gene expression profile typical of negative energy balance with low cocaine- and amphetamine-regulated transcript mRNA and elevated OB-Rb. Melanocortin 3-receptor mRNA levels were indistinguishable in short-day and long-day food-restricted hamsters. The hypothalamic correlates of food restriction in short days included up-regulated anabolic neuropeptides and increased OB-Rb mRNA. Low plasma leptin is integrated differently in short-day and long-day restricted animals, and seasonally-inappropriate body weight in either photoperiod engages the compensatory neuropeptide systems involved in the defense of body weight.
雄性西伯利亚仓鼠在光周期变化时会经历生理体重变化。通过在长日照条件下限制食物摄入以模拟短日照时的体重减轻，或者在短日照体重减轻的基础上叠加食物限制，来检验以下假设：即使下丘脑所诱导的体重变化幅度相似，下丘脑也能区分由强制负能量平衡（不适当体重）引起的体重变化和季节性的、适当的体重变化。短日照体重减轻伴随着弓状核中POMC和瘦素受体（OB-Rb）mRNA的减少，但可卡因和苯丙胺调节转录物（CART）升高。与自由采食的长日照对照组相比，弓状核中黑皮质素3受体基因表达减少，但腹内侧核中升高。长日照限制动物的体重减轻产生了典型的负能量平衡基因表达谱，CART mRNA水平低而OB-Rb升高。短日照和长日照食物限制仓鼠的黑皮质素3受体mRNA水平没有差异。短日照条件下食物限制的下丘脑相关变化包括合成代谢神经肽上调和OB-Rb mRNA增加。低血浆瘦素在短日照和长日照限制动物中的整合方式不同，并且在任何一种光周期中，季节性不适当的体重都会激活参与体重防御的代偿性神经肽系统。
